PMMA, also known as acrylic, commonly known as “plexiglass”, has excellent optical properties and resistance to weather changes. The penetration of white light is as high as 92%. It has room temperature creep characteristics, and with the increase of load and time, it can cause stress cracking. PMMA has good impact resistance. PMMA lampshade products have very low birefringence.
1. Transparency: PMMA is an amorphous polymer, and the arrangement of its internal molecules will not interfere with the speed of light entering it when passing through each part, so it can make the light go at the same speed (ie uniform refractive index), It will not cause the light scattered on all sides to interfere with each other. Therefore, PMMA has excellent optical properties and high light transmittance (90-92%, depending on the wavelength).
A sheet or rod with an extremely smooth surface, even when bent to a certain limit, the light that enters from one end can be reflected in its interior, and finally emitted from the other end, just like water flowing through a pipe (a certain Curvature refers to the angle between the bent position and the original position, which cannot exceed 42°; when the bend is in an arc shape, the arc radius must be greater than 3 times the rod diameter or sheet thickness). But when a certain part of the surface is sanded, light can escape from here and show light. This feature can be used to manufacture edge light emitting devices, surgical medical instruments, etc.
2. Mechanical properties: The mechanical strength of PMMA lampshade products is more than 10 times higher than that of ordinary glass, but the strength is only moderate compared with other plastics. Its shortcomings are light and brittle, easy to crack (or silver streaks), low surface hardness, easy to scratch and lose gloss; poor wear resistance, the static friction coefficient between them is 0.8, and the dynamic friction coefficient for steel is 0.45～0.50, so it is easy to scratch and sand.
3. Electrical performance: The electrical performance of PMMA lampshade products is good, especially under low frequency working conditions. However, some of its electrical properties are unique: the dielectric loss tangent value decreases with increasing frequency. Temperature and frequency have an effect on the dielectric constant, while climate and humidity have little effect on electrical performance. But its electrical performance is worse than PE and PS.
4. Thermal performance: The heat resistance of PMMA is not good enough, and the use temperature is only 80°C. The monomer can be copolymerized and crosslinked with ethylene glycol acrylate or propylene methacrylate to improve heat resistance. The specific heat of PMMA is lower than that of most thermoplastics, which facilitates its rapid plasticization by heat. In addition, it has a certain degree of cold resistance, and the impact strength changes little at low temperature -50～-60℃.
5. Chemical properties: PMMA has a certain chemical resistance, but it weakens with increasing temperature. Strong chemical resistance to gas, long-term contact with ozone and sulfur dioxide, no corrosion; chlorine can corrode its surface. It can be dissolved in ethyl acetate or butyl ester, glacial acetic acid, chloroform, benzene, etc.; it can absorb various alcoholic organic compounds, make the volume expand, the surface is rough and hairy, but it is insoluble in aliphatic compounds.
6. Weather resistance: PMMA lampshade products have excellent weather resistance, with little transparency and color change after years of exposure to tropical climates.
Dongguan Lianzhen Optoelectronics Technology Co., Ltd specialize in the production of extruded (extruded) plastic profiles. The main products are: PVC cold top/hard top extrusion, various (PVC, ABS, PP, PE, PC, PMMA, etc.) plastic extrusion profiles, pipes and Bar, PC/PMMA lampshade, wire duct, PVC soft rubber strip, two-color co-extrusion, extrusion die, etc.
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Post time: Jan-13-2021